1. Field of the Invention
The present invention relates to a tape cassette. More particularly, it relates to a tape cassette which has a cylindrical tape guide having a slit whose position is fixed in the case.
2. Description of the Prior Art
A guide for guiding the running of a tape is disposed in a tape cassette or a cartridge having at least one reel for winding the tape in a case.
FIG. 1 is a schematic view of a conventional video tape cassette. In FIG. 1, the reference numeral (1) designates a lower half of a case in which a tape (4) is wound on a feeding reel (2) and within which the winding reel (3) are held. The tape (4) is unwound from the feeding reel (2), along a guide (5) and a roller (6) to the outer part of the case and is fed past a roller (6') and a guide (5') and wound on the winding reel (3).
The tape is run unwound to the outer part in the video tape cassette etc., whereby the friction between the tape and the guide should be minimized. The tape is for example unwound at high speed such as in a computer, etc. the friction should accordingly be minimized and for this reason a shaved round bar is usually used as the guide. In order to prepare properly such a round bar, many processes for shaving and polishing etc. are needed thus resulting in high cost of production.
The conventional guides (5), (5') are prepared by shaving and polishing a round bar and tapping the same to form taps (8) for screwing at the centers of the upper and lower edges as shown in FIG. 2. The guides are fixed between the lower half of the case and an upper half-case (9) with screws (11), (12).
In order to overcome the disadvantage of the conventional tape cassette, the inventors has proposed new type cassette tape in their previous application (Japanese Utility Model Application No. 71275/1976). The structure thereof will be explained hereinbelow.
The guide of such application is different from the above-mentioned roller and is not rotated. Accordingly, it is not always necessary to have smooth surface for all cylindrical surfaces. That is, the surface which is not contacted with the tape need not be smooth. Therefore, the guide can be formed by bent one sheet of a plate in cylindrical shape and the seam, i.e. the slit is disposed to a position such that the tape is not contacted to the seam.
The previous invention has been attained by such consideration. The embodiment of the previous invention is illustrated in FIG. 4 which shows a guide (13) for the cassette tape. The guide (13) is prepared by bending one sheet of a mental plate in a cylindrical shape whereby a slit (14) is formed.
In order to set the cylindrical tape guide (13) on the cassette tape, the guide can be fixed between the upper and lower halfs of the case from both sides with screws.
The thickness of the tape guide (13) can be made relatively thin by bending a plate in a cylindrical shape. Accordingly, as shown in FIG. 5, the tape guide (13) can be fitted on a pole (17) projected from the lower half-case (1) or the upper half-case (9) as one piece (In FIG. 5, it is projected from the lower half (1) of the case and the pole (17) is fixed to the other half of the case (in FIG. 5, it is the upper half (9) of the case) with a screw (18).
As shown in FIG. 6, the projected part (23) of the upper half (9) of the case can be fitted in the pole (17) to be fix instead of thereto utilizing a screw.
As shown in FIG. 7, the cylindrical tape guide (13) can be fitted to the inner part of the cylindrical frame (19) of one half of the case (in FIG. 7, it is the lower half (1) of the case) to fix them.
In all cases, the fitting is further found to be satisfactory by utilizing the resilient effect of the cylindrical tape guide (13) with the slit (14).
In the tape cassette proposed in the previous invention, the cylindrical tape guide has the above described slit and accordingly, it is necessary that the slit should be disposed to prevent contact with the tape.